Plastic pipe cutter

ABSTRACT

A plastic pipe cutter comprises a front recess for clamping a workpiece; a front chamber; a rear chamber in communication with the front chamber; a bar shaped cutting device including a front blade, a rear head, and a central shank extended through the front chamber and the rear chamber; a first assembly in the front chamber including a stop plate having a hole with the shank passed through, an activation member having a hole larger than the diameter of the shank with the shank passed through, a first elastic member put on the shank and biased between the stop plate and the activation member; a pivotal trigger with the top thereof engaged with activation member; a second assembly in the rear chamber including a pivotal engagement member and a second elastic member put on the shank and biased between the engagement member and the inner wall of the rear chamber, the engagement member having a hole larger than the diameter of the shank with the shank passed through and an external portion, the edges of the hole of the engagement member being in contact with the shank in a storage position; and a third elastic member put on the shank and biased between the enlarged head and the rear of the cutter. By continuing to grip and subsequently release the trigger, the blade is pushed toward the recess to cut the workpiece.

FIELD OF THE INVENTION

[0001] The present invention relates to cutters and more particularly toa plastic pipe (e.g., PVC pipe) cutter with enhanced safety andconvenience features.

BACKGROUND OF THE INVENTION

[0002] Conventionally, user uses a saw to cut a plastic pipe (eg., PVCpipe) which is placed on a supporting ground or stand. It is known thata PVC pipe substantially has a smooth surface and a predeterminedhardness. Hence, PVC pipe tends to slide with respect to the saw and/orthe saw tends to move away from the desired cutting position on PVCpipe. This may cause a number of problems. For example, user may be hurtby the saw carelessly. Further, the operating speed is slow.Furthermore, the finished pipe is not aesthetically pleasing.

[0003] Thus, it is desirable to provide a new and improved plastic pipecutter in order to overcome the above drawbacks of prior art.

SUMMARY OF THE INVENTION

[0004] It is an object of the present invention to provide a plasticpipe cutter comprising a front recess for damping a workpiece; a frontchamber in the rear of the recess; a rear chamber in communication withthe front chamber; a substantially elongate bar shaped cutting deviceincluding a front blade, a rear enlarged head, and a shank coupledbetween the blade and the enlarged head, the shank being extendedthrough the front chamber and the rear chamber to project beyond therear of the cutter; a first assembly disposed in the front chamber, thefirst assembly including a stop plate having a hole with the shankpassed through, an activation member having a hole larger than thediameter of the shank with the shank passed through, a first elasticmember put on the shank and biased between the stop plate and theactivation member; a trigger pivotably secured to the lower portion ofthe cutter by a pin adjacent the activation member, the top of thetrigger being engaged with the lower portion of the activation member; asecond assembly disposed in the rear chamber, the second assemblyincluding an engagement member and a second elastic member put on theshank and biased between the engagement member and the inner wall of therear chamber, the engagement member having a hole larger than thediameter of the shank with the shank passed through and a pin on the topfor pivotably securing to the cutter, the lower portion of theengagement member being projected downwardly from the cutter, theengagement member being obliquely disposed such that the edges of thehole of the engagement member are in contact with the shank in a storageposition; and a third elastic member put on the shank and biased betweenthe enlarged head and the rear of the cutter. By continuing to grip andsubsequently release the trigger, it is possible to push the bladetoward the recess to cut a workpiece.

[0005] The above and other objects, features and advantages of thepresent invention will become apparent from the following detaileddescription taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a side view in part section of a first preferredembodiment of plastic pipe cutter according to the invention;

[0007]FIG. 2 is a view similar to FIG. 1 wherein the cutter isactivating;

[0008]FIG. 3 is a view similar to FIG. 1 wherein the blade has beenpushed to engage with and cut a workpiece;

[0009]FIG. 4 is a view similar to FIG. 1 wherein the blade has beenpulled to disengage from the workpiece after finishing cutting; and

[0010]FIG. 5 is a side view in part section of a second preferredembodiment of plastic pipe cutter according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Referring to FIG. 1, there is shown a plastic pipe cutterconstructed in accordance with the invention comprising a body 11consisting of two identical housings 10. A recess 12 is formed at thefront of body 11 for clamping a workpiece (e.g., PVC pipe not shown). Afront chamber 14 in the rear of the recess 12 and a rear chamber 15 incommunication with front chamber 14 are formed within body 11. Asubstantially elongate bar shaped cutting device 20 comprises a frontblade 21, a rear enlarged head 23, and a shank 22 coupled between blade21 and enlarged head 23. Shank 22 is extended through front chamber 14and rear chamber 15 to project beyond the rear of body 11. Within frontchamber 14, there is provided a stop plate 30 having a central hole withshank 22 passed through, an activation member 31 having a central hole311 larger than the diameter of shank 22 with shank 22 passed through,and a first elastic member 32 put on shank 22 and biased between stopplate 30 and activation member 31. Trigger 40 is pivotably secured tothe lower portion of body 11 by a pin 41 adjacent activation member 31.The top of trigger 40 is engaged with the lower portion of activationmember 31. Within rear chamber 15, there is provided an engagementmember 51 and a second elastic member 50 put on shank 22 and biasedbetween engagement member 51 and the inner wall of rear chamber 15wherein the engagement member 51 has a hole 511 larger than the diameterof shank 22 with shank 11 passed through and a pin 512 on the top forpivotably securing to body 111. The lower portion of engagement member51 is projected downwardly from the body 11. Also, in a storageposition, engagement member 51 is obliquely disposed such that the edgesof hole 511 are in contact with shank 22. A third elastic member 60 isput on shank 22 and biased between enlarged head 23 and the rear of body11.

[0012] The cutting operation of the invention will now be described indetail below by referring to FIGS. 2 and 3. First grip trigger 40 tocause it to pivot about pin 41. Then the upper portion of trigger 40 ispivoted forward to cause the lower portion of activation member 31 topivot clockwise (i.e., activation member 31 is slanted as shown in FIG.2). As such, the edges of hole 311 are in a tight contact with shank 22.Also, first elastic member 32 is compressed and in turn shank 22 isforced to move forward. At the same time, engagement member 51 ispivoted clockwise by the moving shank 22. Also, second elastic member 50is compressed and in turn an allowance (i.e., gap) between the shank 22and hole 511 is formed. Hence, shank 22 is easier to move. Further,third elastic member 60 is compressed by the enlarged head 23. When thegripping force on trigger 40 is released temporarily, the moving ofshank 22 is halted. Then the engagement member 51 is pivotedcounterclockwise by the expansion of second elastic member 50 to causethe edges of hole 511 to contact with shank 22 again, thereby holdingshank 22 in place. Further, activation member 31 is pivotedcounterclockwise by the expansion of first elastic member 32 to form anallowance (i.e., gap) between the shank 22 and hole 311. Hence, trigger40 is pivoted counterclockwise to its original position by the alsocounterclockwise pivoted activation member 31. By repeating aboveoperation, it is possible to push blade 21 toward recess 12 untilengaging with and further cutting the workpiece.

[0013] Referring to FIG. 4, after finishing cutting and removing theworkpiece simply pivot trigger engagement member 51 counterclockwise todisengage hole 511 from shank 22 (i.e., a gap is formed between theshank 22 and hole 511). Hence, the compression force on third elasticmember 60 is released and in turn enlarged head 23 is pushed outward bythe expanding third elastic member 60 until back to the originalposition of enlarged head 23.

[0014] Referring to FIG. 5, a second embodiment of the invention isshown. It is noted that first, second, and third elastic members arehelical springs in the first embodiment. But the third elastic member 60is replaced by a fourth elastic member (e.g., expansion spring) 70.Fourth elastic member 70 is anchored in front chamber 14 and has one endsecured to the rear of blade 21 and the other end secured to the innerwall of front chamber 14. The second embodiment has the same effect asthe first one,

[0015] While the invention has been described by means of specificembodiments, numerous modifications and variations could be made theretoby those skilled in the art without departing from the scope and spiritof the invention set forth in the claims.

What is claimed is:
 1. A plastic pipe cutter comprising: a front recessfor clamping a workpiece; a front chamber in said rear of said recess; arear chamber in communication with said front chamber; a substantiallyelongate bar shaped cutting means including a front blade, a rearenlarged head, and a shank coupled between said blade and said enlargedhead, said shank being extended through said front chamber and said rearchamber to project beyond said rear of said cutter; a first assembly insaid front chamber, said first assembly including a stop plate having ahole with said shank passed through, an activation member having a holelarger than said diameter of said shank with said shank passed through,a first elastic member put on said shank and biased between said stopplate and said activation member; a trigger pivotably secured to saidlower portion of said cutter by a pin adjacent said activation member,said top of said trigger being engaged with said lower portion of saidactivation member; a second assembly in said rear chamber, said secondassembly including an engagement member and a second elastic member puton said shank and biased between said engagement member and said innerwall of said rear chamber, said engagement member having a hole largerthan said diameter of said shank with said shank passed through and apin on said top for pivotably securing to said cutter, said lowerportion of said engagement member being projected downwardly from saidcutter, said engagement member being obliquely disposed such that saidedges of said hole of said engagement member are in contact with saidshank in a storage position; and a third elastic member put on saidshank and biased between said enlarged head and said rear of saidcutter; whereby continue to grip and subsequently release said trigger,said blade is operable to push toward said recess to cut the workpiece.2. The cutter of claim 1, wherein each of said elastic members is ahelical spring.
 3. A plastic pipe cutter comprising: a front recess forclamping a workpiece; a front chamber in said rear of said recess; arear chamber in communication with said front chamber; a substantiallyelongate bar shaped cutting means including a front blade and a shankextended through said front chamber and said rear chamber; a firstassembly in said front chamber, said first assembly including a stopplate having a hole with said shank passed through, an activation memberhaving a hole larger than said diameter of said shank with said shankpassed through, a first elastic member put on said shank and biasedbetween said stop plate and said activation member; a trigger pivotablysecured to said lower portion of said cutter by a pin adjacent saidactivation member, said top of said trigger being engaged with saidlower portion of said activation member; a second assembly in said rearchamber, said second assembly including an engagement member and asecond elastic member put on said shank and biased between saidengagement member and said inner wall of said rear chamber, saidengagement member having a hole larger than said diameter of said shankwith said shank passed through and a pin on said top for pivotablysecuring to said cutter, said lower portion of said engagement memberbeing projected downwardly from said cutter, said engagement memberbeing obliquely disposed such that said edges of said hole of saidengagement member are in contact with said shank in a storage position;and a third elastic member in said front chamber, said third elasticmember secured between said rear of said blade and said inner wall ofsaid front chamber; whereby continue to grip and subsequently releasesaid trigger, said blade is operable to push toward said recess to cutthe workpiece.
 4. The cutter of claim 3, wherein each of said first andsaid second elastic members is a helical spring and said third elasticmember is an expansion spring.